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You might want to also check out the extcal calendar/event module. Users can submit events, etc. to the calendar, and it has fields for contact, location, etc.
The other nice thing...people (potential volunteers) on your website who see the event posting can RSVP to say that they will attend/help, so you can get a good idea of what your turnout might look like. i.e. - the event organizer can check to see that x number of people have confirmed that they will help, etc. It also has a nice feature on the admin side that allows you to send a mass email to those that RSVPd for a particular event to remind them that it is coming up soon.
Just a thought...